The force.js module shows how to use the [Nforce](nforce package to interact with data on force.com. To use this module, you need to:
Create a Connect App with API access in Salesforce and copy down your OAuth consumer credentials. https://help.salesforce.com/apex/HTViewHelpDoc?id=connected_app_create.htm
Force.com access patterns: per user or named principal This sample app is configured to access Force.com using a "named principle". This means that all access happens through a single master user configured on the server. If you use this approach then you don't need the Oauth redirect URI (you can use 'https://localhost/oauth/return').
The other pattern is to authenticate individual uses. In this case you will need to implement the Saleforce oauth flow and redirect endpoint on the server and store the SF session id with the user record.
For our example you need a username, password, AND the security token. Visit the settings for the user account to request the security token by email.
Now setup the following environment variables:
SF_OAUTH_CLIENT_ID - Oauth consumer key
SF_OAUTH_CLIENT_SECRET - Oauth consumer secret
SF_OAUTH_REDIRECT_URI - Oauth redirect URI. Whatever you entered into Salesforce.
SF_USERNAME - Username of the Salesforce user
SF_PASSWORD - Password of the Salesforce user
SF_TOKEN - Security token for the Salesforce user